The present invention comprises a new and distinct cultivar of Osteospermum, botanically known as Osteospermum hybrida, and hereinafter referred to by the cultivar name ‘SAKOST021’. ‘SAKOST021’ originated as a naturally occurring, whole plant mutation of ‘Kakegawa AU20’ (U.S. Plant Pat. No. 18,980) discovered in 2005 in Kakegawa, Japan. ‘SAKOST021’ has a deeper yellow flower color than that of ‘Kakegawa AU20’.
From 2006 to 2007, the ‘SAKOST021’ was vegetatively propagated from cuttings and re-evaluated in an open field and in a greenhouse. The stability of the distinct characteristics of the new variety was confirmed. The selection was subsequently named ‘SAKOST021’.